Theory of helicenic hydrocarbons. Part 2: Chemical formulas

1993 ◽  
Vol 4 (5) ◽  
pp. 303-316 ◽  
Author(s):  
S. J. Cyvin ◽  
B. N. Cyvin
Keyword(s):  
Chemical Formulas

scholarly journals Nontargeted mass-spectral detection of chloroperfluoropolyether carboxylates in New Jersey soils

Science ◽  
2020 ◽  
Vol 368 (6495) ◽  
pp. 1103-1107 ◽  
Author(s):  
John W. Washington ◽  
Charlita G. Rosal ◽  
James P. McCord ◽  
Mark J. Strynar ◽  
Andrew B. Lindstrom ◽  
...  
Keyword(s):  
New Jersey ◽  
New Hampshire ◽  
Additional Data ◽  
The United States ◽  
Environmental Persistence ◽  
Mass Spectral ◽  
Spectral Detection ◽  
Global Concern ◽  
Airborne Transport ◽  
Chemical Formulas

The toxicity and environmental persistence of anthropogenic per- and poly-fluoroalkyl substances (PFAS) are of global concern. To address legacy PFAS concerns in the United States, industry developed numerous replacement PFAS that commonly are treated as confidential information. To investigate the distribution of PFAS in New Jersey, soils collected from across the state were subjected to nontargeted mass-spectral analyses. Ten chloroperfluoropolyether carboxylates were tentatively identified, with at least three congeners in all samples. Nine congeners are ≥(CF2)7. Distinct chemical formulas and structures, as well as geographic distribution, suggest airborne transport from an industrial source. Lighter congeners dispersed more widely than heavier congeners, with the most widely dispersed detected in an in-stock New Hampshire sample. Additional data were used to develop a legacy-PFAS fingerprint for historical PFAS sources in New Jersey.

scholarly journals Determination of ramipril in human plasma and its fragmentation by UPLC-Q-TOF-MS with positive electrospray ionization

2015 ◽  
Vol 65 (2) ◽  
pp. 159-169 ◽  
Author(s):  
Paweł Szpot ◽  
Grzegorz Buszewicz
Keyword(s):  
Electrospray Ionization ◽  
Human Plasma ◽  
Ultra Performance Liquid Chromatography ◽  
High Accuracy ◽  
Coefficient Of Determination ◽  
Limit Of Quantification ◽  
Flight Mass Spectrometry ◽  
Tof Ms ◽  
Chemical Formulas

Abstract This report presents the application of ultra-performance liquid chromatography coupled to quadrupole time-of-flight mass spectrometry with positive electrospray ionization, to determine ramipril in human plasma. First, the proteins in human plasma were precipitated using acetonitrile, then the supernatant was extracted by ethyl acetate at pH 3 and finally, the extract was analyzed using a UPLC-QTOF- MS system. The method was validated and the coefficient of determination (R2) was > 0.999, the lower limit of quantification (LLOQ) was 0.5 ng mL-1. Precision, recovery and stability were determined for three different concentrations of ramipril. RSD for this method ranged from 3.3 to 8.6 %. The intra-day mean recovery was from 65.3 to 97.3 %. In addition, the fragmentation of ramipril was studied. Due to high resolution of the spectrometer, it was possible to measure fragment masses accurately and determine their molecular and chemical formulas with high accuracy.

scholarly journals Synthesis and Characterization of Mercury(II) Complexes Containing 2,9-Dimethyl-1,10-phenanthroline by Sonochemical Method

2013 ◽  
Vol 2013 ◽  
pp. 1-6 ◽  
Author(s):  
M. Ranjbar ◽  
E. Malakooti ◽  
S. Sheshmani
Keyword(s):  
Thermal Analysis ◽  
Stainless Steel ◽  
Synthesis And Characterization ◽  
Particle Sizes ◽  
Sonochemical Method ◽  
Reaction Conditions ◽  
Mercury Acetate ◽  
Crystalline Complexes Of ◽  
Chemical Formulas

Synthesis and characterization of microstructured crystalline complexes of [HgI2(C14H12N2)] and [HgBr2(C14H12N2)] were carried out from the reaction between 2,9-dimethyl-1,10-phenanthroline, mercury acetate, KI, and KBr, respectively, in methanol by sonochemical method. The reaction conditions were optimized under ultrasonic irradiations and without it. Characterization of the complexes was performed by elemental analysis, XRD, SEM, FTIR, and thermal analysis (TG/DTA). The results showed that sonochemical method caused significant reduction of the reaction time. Then the products were put under supercritical condition in a Teflon-lined, stainless-steel Parr bomb container and heated at 150°C for 48 h. The results showed that the chemical formulas of the complexes were not changed; however, the particle sizes were reduced and porosity increased.

Sign in / Sign up

Export Citation Format

Share Document